Four Types of Evidence in a Criminal Investigation

What are the four types of evidence in a criminal investigation? A: Evidence is any actual data (information), which can be presented in various forms. The actual data relevant to the correct resolution of the case can be obtained (determined) by the court by explanations of the parties, third parties and their representatives, testimony, written and material evidence, expert opinions. Basic types of the evidence comprise physical, documentary, demonstrative, and a testimony kind. The evidence is a type of information concerning certain issues received by the investigatory process.

Physical evidence is a type of evidence is an actual object that can be touchable and investigated. Documentary evidence can be in the form of a letter, receipt, testaments, etc. Photos and videos or chats can present demonstrative type. Witnesses usually deliver testimony kind of evidence.

What are individual characteristics? Give an example of an individual characteristic? A: Individual characteristic is a type of evidence that presents an induvial description of a certain object.

On the contrary, a class characteristic is a characteristic presenting feature of a certain class of objects. It is related to a certain group. The second type of features, particularly class characteristics turned to be more useful and efficient in the investigatory process, as it enables to receive more data acting according to the exclusion method.

What are physical and chemical properties? Give an example of each. A: Each object, particularly evidence, possesses some properties enabling to identify this particular object within a variety of available ones. There two basic type of properties – physical and chemical. Physical properties can be examined without the conduct of any experiments. Moreover, they cannot influence chemical properties of an object. To the physical properties of an object belong, for example, color and smell. Chemical properties can change the chemical features of a matter, and they influence molecular composition. These chemical features can undergo various reactions and change its characteristics. To this group of properties belong, for example, the reactivity of water, the content of liquids in blood, etc.

What do forensic scientists do to collect and preserve soil samples? A: The task of forensic scientists is to carefully collect soil samples and take them to the lab, maximally avoiding an influence of external factors. Their samples are very sensitive and specific. The soil is a physical type of evidence, and it can change the influence of various factors. That is why an expert has to be maximally careful to receive exact and credible results. They have to try to maximally preserve the primary features of the evidence.

Critical thinking questions

Why do you think forensic scientists are so careful that the tests they do are sensitive, reproducible, and specific? What might happen if they were less careful about this? A: In my opinion, the task of the forensic scientists is to be maximally careful to preserve all the chemical data that the soil samples may enable to get. If they are less careful about their samples, the test results may be not very accurate. What is more, the samples may provide no info, which may be useful in the investigatory process.

Which type of evidence do you think is most useful in an investigation? Why? A: I believe the most credible and useful type of criminal evidence is a physical sample. Physical evidence includes material objects that have properties that reflect the circumstances of a crime in the form of traces, origin, etc. The information contained in material objects, transmitted through direct perception of the features of the subject is the most credible way to receive data that may apply to the investigatory process.

Why do you think that forensic scientists continue to look for class characteristics given their limitations? A: The task of forensic scientists is demands the responsible attitude, as they need to provide the investigatory experts with the data, that may enable them to reveal a crime. A tendency according to which they continue to look for class characteristics given their limitations turned to be the most prolific. The reason for that is simple – it enables to receive the data enabling to find the answer maximally quickly and effectively. For example, the characteristics of various types of guns can be used as a helpful tool in the determination of weapons used by a criminal in the process of committing a crime.